This invention relates generally to lighting techniques, and provides a method and device using an electrodeless plasma lighting device having a dielectric waveguide of a dielectric constant of less than two. More particularly, the invention provides a method and apparatus having an electrodeless plasma lighting device using a ceramic resonator structure of a dielectric constant of less than two. The invention can be applied to a variety of applications including a warehouse lamp, stadium lamp, lamps in small and large buildings, vehicle headlamps, aircraft landing, bridges, warehouses, ultraviolet water treatment, agriculture, architectural lighting, stage lighting, medical illumination, microscopes, projectors and displays, any combination of these, and the like.
From the early days, human beings have used a variety of techniques for lighting. Early humans relied on fire to light caves during hours of darkness. Fire often consumed wood for fuel. Wood fuel was soon replaced by candles, which were derived from oils and fats. Candles were then replaced, at least in part by lamps. Certain lamps were fueled by oil or other sources of energy. Gas lamps were popular and still remain important for outdoor activities such as camping. In the late 1800, Thomas Edison, one of the greatest inventors of all time, conceived the incandescent lamp, which uses a tungsten filament within a bulb, coupled to a pair of electrodes. Many conventional buildings and homes still use the incandescent lamp, commonly called the Edison bulb. Although highly successful, the Edison bulb consumed much energy and was generally inefficient.
Fluorescent lighting replaced incandescent lamps for certain applications. Fluorescent lamps generally consist of a tube containing a gaseous material, which is coupled to a pair of electrodes. The electrodes are coupled to an electronic ballast, which helps ignite the discharge from the fluorescent lighting. Conventional building structures often use fluorescent lighting, rather than the incandescent counterpart. Fluorescent lighting is much more efficient than incandescent lighting, but often has a higher initial cost.
Shuji Nakamura pioneered the efficient blue light emitting diode, which is a solid state lamp. The blue light emitting diode forms a basis for the white solid state light, which is often a blue light emitting diode within a bulb coated with a yellow phosphor material. Blue light excites the phosphor material to emit white lighting. The blue light emitting diode has revolutionized the lighting industry to replace traditional lighting for homes, buildings, and other structures.
Another form of lighting is commonly called the electrodeless lamp, which can be used to discharge light for high intensity applications. Frederick M. Espiau was one of the pioneers that developed an improved electrodeless lamp. Such electrodeless lamp relied upon a solid ceramic resonator structure, which was coupled to a fill enclosed in a bulb. The bulb was coupled to the resonator structure via RF feeds, which transferred power to the fill to cause it to discharge high intensity lighting. The solid ceramic resonator structure has a limited dielectric constant. An example of such a solid ceramic waveguide is described in U.S. Pat. No. 7,362,056, which is hereby incorporated by reference herein. Although somewhat successful, the electrodeless lamp still had many limitations. As an example, electrodeless lamps have not been successfully deployed in high volume for general lighting applications. Additionally, the conventional lamp also uses a high frequency and has a relatively large size. Accordingly, the conventional lamp is often cumbersome and difficult to manufacture and use. These and other limitations of the conventional lamp are described throughout the present specification and more particularly below.
From the above, it is seen that improved techniques for lighting are highly desired.